Filter press fluorine cell with carbon connectors

ABSTRACT

This invention relates to a filter press type of cell wherein the connection of an anode to the cathode of an adjacent cell is through a carbon connector. Individual cells have their ends protected by a Teflon end cover plate. The carbon connector between cells passes, by means of a press fit, through a Teflon bushing. A metal diaphragm fits across each cell intermediate its ends, the diaphragms being insulated from the adjacent metal body of the cell by Teflon gaskets. The cell bath fills the cells and extends into hydrogen and fluorine risers at the top of each cell.

United States Patent Juckniess June 27, 1972 [54] FILTER PRESS FLUORINE CELL WITH 3,402,117 9/1968 Evans ..204/268 CARBON CONNECTORS FOREIGN PATENTS OR APPLICATIONS 72 I t P IR. 1 1,054,430 4/1959 Germany ..204/253 [73] Assignee: The Dow Chemlcal Company, Midland,

Mich. Primary Examiner-Winston A. Douglas Assistant Examiner-M. J. Andrews [22] Filed' Much 1,69 Attorney-Griswold & Burdick and Earl E. Ayers [2]] Appl. No.: 804,396

[57] ABSTRACT [52] U.S. Cl. ..204/256, 204/60 This invention relates to a filter press type of cell wherein the [51] Int. Cl. ...B01k 3/10, BOlk l/00 connection of an anode to the cathode of an adjacent cell is [58] Field of Search ..204l252-2'58, 59, through a carbon connector. Individual cells have their ends 204/60, 256 protected by a Teflon end cover plate. The carbon connector 7 between cells passes, by means of a press fit, through a Teflon [56] References Cited bushing. A metal diaphragm fits across each cell intermediate its ends, the diaphragms being insulated from the adjacent UNITED STATES PATENTS metal body of the cell by Teflon gaskets.

l,365,875 l/l92l Ward ..204l256 m cc" bath fills the cells and extends into hydrogen and 4 3,055,81 l 9/1962 Ruff 204/128 fl i risers at the top f each celL 3,119,759 111964 Hoover.......... ...204/256 3,242,065 3/1966 De Nora et al. ..204/256 4 Claims, 3 Drawing Figures PATENTEDJum 1972 ooooo ooo T00 00002009 Zcobooooooooo JToooooooo INVENTOR. POu/R. JucKfl/gSS A 6 6 N T FILTER PRESS FLUORINE CELL WITH CARBON CONNECTORS 7 BACKGROUND OF THE INVENTION This invention relates to electrolytic cells for use in making fluorine and particularly to a filter press type electrolytic cell for such use. Fluorine cells now in use are very complicated structures. The weakest structure is the metal to carbon anode connection in the cell. In practice, it is necessary to rebuild the cells about every 3 or 4 months.

Accordingly, a principal object of this invention is to pro vide an improved electrolytic cell for use in making fluorine.

Another object of this invention is to provide an improved electrolytic cell for use in making fluorine which has lower maintenance requirements than'other similar cells.

A further object of this invention is to provide an improved, simpler electrolytic cell for use in making fluorine which has a relatively low capital cost.

In accordance with this invention, there is provided a filter press type of cell wherein the connection of an anode to the cathode of an adjacent cell is through a carbon connector. Individual cells have their ends protected by a Teflon end cover plate. The carbon connector between cells passes, by means of a press fit, through a Teflon bushing. A metal diaphragm fits across each cell intermediate its ends, the diaphragms being insulated from the adjacent metal body of the cell by Teflon gaskets.

The cell bath fills the cells and extends into hydrogen and fluorine risers at the top of each cell.

The invention, as well as additional objects and advantages thereof, will best be understood when the following detailed description is read in connection with the accompanying drawing, in which:

FIG. 1 is a side elevational view partly in section, of a fluorine cell made in accordance with this invention;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1; and

FIG. 3 is a fragmentary sectional view taken along the line 3--3 of FIG. 1.

Referring to the drawing, there is shown an electrolytic cell device, indicated generally by the numeral 10, composed of cells 12 and 14. The two cells are separated from each other by a common end wall plate element 16 made of metal such as nickel or nickel clad metal, for example.

Each cell has a pair of hollow cylindrically shaped metal body wall elements 18, 20 and 22, 24 in cells 12, 14, respectively. The cell assembly is closed at each end by an end plate element 26, 28, respectively.

Each end plate element 26, 28 and the wall plate element 16 has an axial bore 30, 32, 34, respectively, through which electrode connectors extend.

The bore 34 is of larger diameter than the bores 30, 32. The wall plate element 16 has a Teflon (polytetrafluoroethylene) sheet 36, 38 on each side of it, the sheets 36, 38 having bores which are the same size as and aligned with the bore 34. A two piece Teflon bushing 40 is press fitted through the bore 34 and the bores in sheets 36, 38, with the outwardly extending ends of the bushing 40 fitting tightly against the adjacent sheet 36 or 38, respectively.

A carbon or graphite feed-through rod 42 extends through the bushing 40 in a press fitting relationship therewith. The ends of the feed-through rod are coupled to a carbon anode 44 and a carbon cathode 46, respectively.

The anode 44 lies within the body part 20, and the cathode 46 lies within the body part 22.

Each of the body part elements 18, 20, 22 and 24 is a generally hollow cylinder in configuration and each element has a riser 48, 50, 52, 54, respectively, rising from what is the top of the device when the cells are operatively assembled. In the body elements 20 and 24, from whose headers 50, 54, fluorine is withdrawn, the inner wall part 56, 58, adjacent to the headers 50, 54, respectively, is beveled towards the header in that body element.

The body elements 18, 20 and 22, 24 are separated from each other by a diaphragm 60, 62, respectively. The diaphragms 60, 62 are electrically insulated from the adjacent metal body elements by Teflon gaskets 64, 66 and 68, 70, respectively.

A plate-like metal cathode 76, made of nickel, for example, is disposed in the body element 18. A Teflon gasket sheet 72 electrically insulates the body element 18 from the end plate element 26 and protects the part of the end plate element 26 which is exposed to the cell bath 74 from electrolysis.

The cathode 76 has an electrical lead in the fonn of a ho]- low metal tube 78 which extends perpendicularly from the central part of the cathode 76 and through the bore 30 in the end plate element 26.

An outer hollow tubular metal sleeve element 80 surrounds the lead tube 78, the ends of the element 80 bearing against washer 82 and washer 84, respectively. A bolt 88, engaging threads 86 on the internal surface of the tube 78, is used to pull the cathode 76 tightly against the Teflon sheet 72 to effect a fluid tight seal therewith.

Each of the diaphragms 60, 62 isv usually made of nickel and contains an array of perforations 90 which extend generally across the surface area of the diaphragm except near the top of the adjacent cell body part.

A carbon anode 92 is disposed within the body element 24 and is coupled to a carbon rod 94 which is surrounded by a close fitting thin Teflon separator 96. The rod 94 and Teflon separator 96 fit in press fitting relationship within a metal sleeve 98 which has an outwardly extending flange 100 at the end thereof which extends into the body element 24. The body element 24 is electrically insulated from the end plate 28 by a Teflon sheet 102 which also covers the side of the end plate 28 which faces the body element 24. The sleeve 98 has threads 104 on its outer end.

An outer sleeve 106 surrounds the part of the sleeve 98 which extends out of the end plate 28. An insulating gasket 108 fits across the outer end of the outer sleeve 106, insulating the nut 110 on the threads 104 from the sleeve 106. The nut l 10 is tightened to draw the flange 100 of the sleeve 98 tightly against the Teflon sheet 102, making a seal between the flange and the sheet 102.

With the apparatus filled to a level in the output headers, direct current of suitable polarity is applied to the anode lead 94 and the cathode lead 78 from any suitable source (not shown).

Upon application of current to the apparatus, fluorine liberated at the anodes rises through the cell bath and passes out through risers 50, 54. Similarly, hydrogen liberated at the cathodes rises and leaves the apparatus through the risers 48, 52. In practice, the cells are filled with bath which a mixture of potassium fluoride and hydrogen fluoride containing 40 to 50 percent hydrogen fluoride. Since corrosion is such a small problem in this cell, higher hydrogen fluoride values can be used. In conventional cells, hydrogen fluoride is kept at 42 percent or less. Higher hydrogen fluoride values give lower voltages and better power economy. The cell may be operated at 80 to C., the higher temperature giving lower voltage but higher hydrogen fluoride in the hydrogen and fluorine.

While the diaphragms 60, 62 are preferably made of nickel because of its long life in such usage, magnesium or iron are also operable for such use.

The entire assembly as shown in FIG. 1 is, of course, held together in sandwiched" form by means of suitable clamping means, not shown.

It is also obvious that more cell assemblies may be connected in series than those shown in FIG. 1.

It is also practical to provide larger diameter cell assemblies in which a plurality of anodes and cathodes are provided in each body part of the assembly. For example, four feed through elements spaced in an array might be used, with an electrode coupled to each feed through element. The need for such assemblies occurs in bigger cells when it is impractical or uneconomical to provide a single, large electrode for the assembly.

What is claimed is:

1. Electrolytic cell apparatus comprising a plurality of cell assemblies joined together in sandwiched end-to-end series relationship, each cell including a pair of tubular nickel body parts separated from each other by a foraminous nickel diaphragm sheet, each of said body parts having a header at the top part of said cell, electrically insulating gasket means disposed between said diaphragm and said body parts, each cell being closed by an end plate which is physically isolated from any cell bath in the apparatus and electrically insulated from said body parts by sheet-like gasket means, at least one end plate of each cell also functioning as an end plate of an adjacent cell, a feed through carbonaceous element, said carbonaceous feed through element extending through an end plate which is common to two adjacent cells with an end extending into the adjacent body parts, said feed through element being electrically insulated and physically separated from said end plate by bushing means, a pair of carbonaceous electrode elements, one carbonaceous electrode element being attached to each end of said feed through element, each other end plate having an electrode lead extending therethrough and having an electrode coupled thereto and disposed within one of said body parts which is adjacent to an end plate, one of said electrodes attached to one of said other end plates being a carbonaceous anode and being rigidly coupled to a carbonaceous electrical lead which is electrically insulated from the end plate through which it extends, and the other of said electrodes attached to the other of said other end plates being a nickel cathode electrode having a rigid metal electrical lead bonded thereto, said nickel electrode being electrically insulated from said body parts.

2. Apparatus in accordance with claim 1, wherein the inner wall of the body part lying adjacent to the headers in the body part containing the anodes of said apparatus are beveled towards said headers.

3. Apparatus in accordance with claim I, wherein metal parts of said apparatus are made of nickel.

4. Apparatus in accordance with claim 1, wherein said diaphragms are non-foraminous at the top part thereof adjacent to said headers.

i i t l 

2. Apparatus in accordance with claim 1, wherein the inner wall of the body part lying adjacent to the headers in the body part containing the anodes of said apparatus are beveled towards said headers.
 3. Apparatus in accordance with claim 1, wherein metal parts of said apparatus are made of nickel.
 4. Apparatus in accordance with claim 1, wherein said diaphragms are non-foraminous at the top part thereof adjacent to said headers. 